270WSM great grouping

[Methow Packer]

Your opinion appreciated. My 270WSM is shooting bug hole groups ( 1/4 - 3/8) using 140 Berger Classic .020 off lands using 63.0 gr 7828SC . Fantastic but with a little sticky bolt lift, slight ejector marks. Primers not too bad. Question about best approach. Drop charge weight by .5 grain and leave the .020 seating depth and see and or adjust seating depth to reduce pressure. Increase depth say .025 or decrease .015. Not sure of direction to go. I hate to loose this tight grouping but i'd like to reduce the pressure too. I know bullets at or in the lands increases pressure.

 

[Hawk in WY]

At .020 off the lands you don't have much to play with. I happen to have a .300 Win Mag load open on QuickLOAD. Increasing the COAL by 0.020 reduces pressure by 500 psi. Probably, not enough to make a difference.

You don't want to be touching the lands particularly in a hunting rifle. Pressure spikes and you can pull a bullet unloading if well into the lands. I would reduce the powder charge in 0.2 grain steps and see what you get. There will be a lower accuracy node eventually.

You also need to take into account the temperature at which you shot the good groups. If in summer time, pressure might be just fine at lower temperatures. 7828SC is a bit temperature sensitive. Of course, the accuracy might not be as good at lower temperatures as well.

Good luck.

 

[WeiserBucks]

Sounds like you definitely have a max load established, only you can decide if it's safe .

 

[jjmp]

i'd keep the seating depth the same, and reduce the powder charge .5 grain, don't shoot that many bergers, put have found similar tight grouping loads with normal bullets, the 270WSM is a great performer enjoy, jjmp

 

[Methow Packer]

i'd keep the seating depth the same, and reduce the powder charge .5 grain, don't shoot that many bergers, put have found similar tight grouping loads with normal bullets, the 270WSM is a great performer enjoy, jjmp

Thanks for the reply. Good advice. If I loose these tight groups by reducing the load too much I'll leave 7828 and move on to imr7977. RL26 is looking promising too..